I often wonder if the type and thickness of the keycap plastic chosen dictate what other process can be applied to the plastic; i.e. how much physical texture can be created. If you look closely at the surface of a Realforce key, you'll see they have a physical texture to them, but it differs slightly not only from key to key but from board to board, so I think this is not a simple process. However, even physical texture will wear down over time. I think the coated texture on my 3+ year old FILCO has worn gracefully; slower than some others report, but everyone has differing amounts of oil/dirt/roughness/fingernails at their fingertips. And unless you shine a bright light on my 3 year old keys, then the wear isn't obvious, it blends well.
As for blank Topre keys, blank Realforce keys don't look to be available, but HHKB will be.